Runoff from the abandoned copper mines in Strafford, Vt., sometimes frequented as a swimming spot by Dartmouth students during warm weather, is as acidic as cider vinegar, and poses a serious threat to the surrounding environment.
Bob Walker, director of the Elizabeth Mine Study Group - founded in 1996, shortly after the mine was listed as a pollution hot spot by the New England Interstate Pollution Control - said the mine is a large threat to the surrounding environment.
He said 200 million tons of tailings, or waste, from the mines that were operated between 1793 and 1958 were piled in the valley near the mines. Those piles now are 150 feet high, and cover 40 acres of land.
When the sulfides that are contained in the tailings are exposed to the air, they become sulfates, which turn into sulfuric acid when hit with rain. This sulfuric acid solution dissolves metals from the ground nearby.
This metallic lechate solution has a pH of between 2.2 and 3.3, about the same acidity as cider vinegar, Walker said.
The Copperas Brook carries the lechate from the tailings pile to the Ompompanoosuc River, which is about three quarters of a mile from the mines.
"The stream that's running down to the Ompompanoosuc is pretty much dead," Walker said. "When the lechate gets down to the river, there is a significant effect at the site."
According to Walker, in a recent study, "Above the impacted water, we were getting about 150 insects per netting, but immediately below where the water comes in, we got four insects."
He said the Elizabeth Mines Study Group also did some fish counts, and the numbers of fish in the affected portions of the Ompompanoosuc River are also much lower than in the unaffected areas.
He attributes this decrease in fish to the lack of edible insects available to them as a result of the polluted runoff.
He said so far, the study group has not observed any sort of human health risk, but he said the existence of metals like copper, aluminum, cadmium and zinc in the lechate are not healthy for people to drink.
As of now, the water wells in the surrounding community have not been infiltrated by the polluted water. He said the pollution is limited to the water coming off of the tailings piles, or coming from the old mine shafts themselves.
Walker said the community is working to remedy the pollution the Elizabeth Mines are causing the surrounding environment.
There was a community meeting last night when the remediation consultants and the hydrological consultants who organized the studies of the Elizabeth Mines Study Group discussed their results, and tried to engage the community in conversation.
"We're just trying to let people know what's going on with the project," he said.
He said community members can assist in the cleanup effort by helping to collect water and aquatic samples for further studies, and by helping with the effort to do historic documentation that is necessary before the remediation process can take place.
He said the remediation will probably entail reshaping the tailings pile, capping it with an impermeable clay substance, and redirecting the water around the pile so that acidic lechate does not disseminate throughout the region.
Lauren Worley '99 said a lot of Dartmouth students talk about going to the old copper mines in the summer.
Travis Buono '99 said he went to the abandoned mines during his sophomore summer with the intent of swimming, but came back to Hanover without jumping in.
"It's a place to go," he said. "It's kind of nice."
