SILVERTON – What happens when you plant trees in a pile of mine waste?
We’re about to find out.
The U.S. Forest Service has embarked on a bit of a science experiment this summer, to see if trees, willows and other vegetation are able to take root on a waste pile near the Brooklyn Mine, located on a mountainside northwest of Silverton, said Gretchen Fitzgerald, a forester with the agency.
“Not much has been done with this waste rock,” Fitzgerald said. “But I wanted to try this.”
If successful, the project could have beneficial effects on water quality and set a precedent for the future restoration of toxic areas.
“It’s an experiment,” Fitzgerald said.
According to federal records, the Brooklyn Mine was first dug for its reserves of gold, silver and zinc in the early 1900s, operating on-and-off over the years. The most recent mining activities happened in the mid-1960s and lasted for about two decades.
Eventually, the Brooklyn Mine shut down, leaving behind a complicated mess to clean up.
In the late 1990s, however, the Forest Service began cleaning up the area, diverting mine wastewater discharges from collapsed adits and waste rock piles.
Attention was turned once again to the Brooklyn Mine after it was included in the Environmental Protection Agency’s Bonita Peak Mining District Superfund site, comprised of 48 mining sites around Silverton responsible for degrading water quality in the Animas River.
Because the Brooklyn Mine is located on the San Juan National Forest, the Forest Service is taking the lead on the cleanup there, said Ben Martinez with the San Juan National Forest. But it’s possible previous mining companies could be on the financial hook.
“The EPA along with its federal and state partners are coordinating on site-wide efforts to identify potentially responsible parties at the (Bonita Peak) site,” Martinez said.
In the meantime, federal agencies are going ahead with the cleanup. Martinez said the site is being investigated to find out just how much contamination the Brooklyn Mine is contributing to the headwaters of the Animas, and what the possible right steps are for long-term remediation.
Peter Butler with the Animas River Stakeholders Group said the Brooklyn Mine was included in a list of the top 33 polluting mine sites created by the stakeholders group years ago. He said the wastewater coming out of the mine, especially, poses a problem, leeching heavy metals into Mineral Creek, a tributary of the Animas River.
“It’s one of the higher priority sites,” Butler said. “It’s a drainage with a fair amount of metals.”
While the big picture cleanup is being figured out, projects like Fitzgerald’s tree planting could help with issues associated with the waste rock pile.
For the project, seeds were collected from Engelmann spruce trees right next to the pile, and native flowers were taken from Ophir, a small mountain town 13 miles west of Silverton.
The seeds were sent to a nursery and matured for two years. This summer, interns with Mountain Studies Institute, Southwest Conservation Corps and Outward Bound took on the task of planting 900 spruce trees, 300 flowers and 30 willows.
There’s a bit of technique and skill involved if you want reforested plants at an elevation of 11,000 feet to survive, Fitzgerald said.
“Regular reforestation is tough,” she said. “But it’s even tougher when it’s higher up.”
Planting was delayed this year because of heavy snowpack in the San Juan Mountains this past winter. Using a hoedad, interns dug into the hard ground, spacing spruce trees about 10 feet apart. Flowers were planted a little closer, at about 1- to 2-foot intervals.
“Now, we hope it will seed and spread and grow,” Fitzgerald said.
Fitzgerald said she’s never undertaken a project quite like this, but if the plants take hold, it could stabilize the hillside and keep the waste rock out of the watershed, acting as a sort of filter.
There is some precedent for trying to grow on mine waste in Southwest Colorado.
According to a Mountain Studies Institute report, some of the most significant and enduring problems of the legacy mining in the San Juan Mountains are soil and water quality degradation associated with abandoned mine tailings and waste rock piles.
And a major impediment to reducing the amount of pollution from these sites, according to the report, is the difficulty of reestablishing vegetation.
Mountain Studies Institute tried a few years ago to test the effectiveness of biochar (a charcoal used as a soil alternative, rich in carbon) and straw compost at abandoned mine sites around Silverton.
The results were encouraging: The addition of biochar resulted in a nearly 200% increase in biomass on sites with levels of high acidity. On areas where soil acidity was low, however, biochar increased vegetation by only 6% to 11%.
That’s why the Forest Service’s experiment at the Brooklyn Mine is a little more of a test trial: Fitzgerald said the mine waste rock at the site has low acidity. But, the fact some plants are naturally starting to creep out of the ground nearby is encouraging.
After everything is in the ground, the Forest Service will monitor the project site every few years. The long-term hope, Fitzgerald said, is the project will kick-start natural revegetation farther down on the pile.
Looking out at the buzzing project, where new trees started to dot the otherwise dead hillside, Fitzgerald was hopeful.
“We don’t have to accept this,” she said.
jromeo@durangoherald.com
