Energy & Environment

EPA, Corinth prepare for the Upper Valley’s next mine cleanup

Tailings at the Pike Hill Copper Mine Superfund Site. Photo courtesy of the Environmental Protection Agency

Editor’s note: This story by Frances Mize was first published in the Valley News on July 9.

CORINTH — After a more than 15-year hiatus, the federal Environmental Protection Agency has begun drafting its cleanup plans for Pike Hill Mine.

In 2004, the abandoned copper mine off Richardson Road was deemed a Superfund site, a designation reserved only for the most hazardous polluted areas in the country.

But little has happened since.

Since the EPA first got involved with the site over a decade ago, attention in the community of around 1,400 residents has waned, Corinth Selectboard Chair Rick Cawley said.

“There’s a certain degree of out of sight, out of mind,” Cawley said about Pike Hill, which is more remote and difficult to access than Elizabeth Mine, a recently completed Superfund project just off of Route 132 in Strafford.

But now that time and financial resources have returned to the agency, action at the mine will soon heat up again. EPA cleanup at Elizabeth Mine ended last November, and the agency has been able to turn its attention to Pike Hill.

The area of concern comprises three separate mining areas along with Pike Hill Brook and a tributary to Cookville Brook; the concentration of toxic copper leaching into those streams far exceeds federal and state water quality standards.

Scheduled to begin in 2024, the project is expected to cost between $18 million and $20 million, with the federal government picking up the entire tab, according to EPA Remedial Project Manager Ed Hathaway.

Contaminated runoff from Pike Hill — two of its three mines are owned by Vermont land-holding corporation Second Growth Holdings and the other by an individual — will be addressed through a cleanup that will likely involve moving over 5,000 truckloads of material.

The EPA began sampling again for contaminants at Pike Hill last summer to determine if anything had changed since the initial assessments in the early 2000s.

“The concentrations of toxic copper that were doing damage then are still just as harmful,” Hathaway said of the streams at the Corinth site that have been choked with pollution for decades now.

The damage

The Orange County Copper Belt — a 20-mile stretch of mining sites that extends from South Strafford through Vershire and up into Corinth — ends at Pike Hill and also includes the Elizabeth and Ely mines. Each of these sites made significant contributions to 19th and 20th century copper mining, and after Ely, Pike Hill was the second of the three to close, with operations discontinuing around 1920.

The mining industry left behind significant environmental damage.

In total, across the three mining areas that make up the Pike Hill site, there are over 82,000 cubic yards of sulfide-containing waste rock and mine tailings.

Sulfuric acid, produced when water and oxygen come into contact with the sulfide present in mine waste, leaches toxic metal out of the waste rock and sends it downstream.

Pike Hill Brook in the forest just downstream of the waste piles at the Pike Hill Copper Mine Superfund Site in Corinth. Photo courtesy of the Environmental Protection Agency

In a lab test, all of the fish exposed to water from the contaminated stretch of Pike Hill Brook extending half a mile downstream from the mining site died. Only 15% of fish exposed to water samples from a location 1½ miles downstream of the site survived. That is compared with a 95% survival rate for fish exposed to water downstream of an unimpacted tributary to Pike Hill Brook.

Pike Hill Brook empties into the Waits River, where no contamination has been detected.

Pike Hill Mine also is home to Vermont’s largest known concentration of the threatened eastern small-footed bat, as well as the federally threatened northern long-eared bat. Both species use the underground tunnels for shelter, especially in the winter.

Working with the Vermont Department of Fish and Wildlife, the cleanup effort will avoid damaging the tunnels and ensure that vegetative buffers are left around their openings.

While significant harm is posed to ecological life, there is unlikely to be a human health risk from the mine waste deposits at the Vermont sites, Hathaway said.

The EPA sampled well water for two residences by the site and deemed it clean.

The cleanup

When groundwater doesn’t reach the waste pile at a mine, covering the pile in protective sheeting is enough damage control. However, as is the case at Pike Hill, the close proximity of groundwater to the waste pile has led to dangerous leaching and requires a strategy that Hathaway describes as “excavation, consolidation and capping.”

Waste scattered throughout the site would be gathered at a single location, where a cleanup crew could smother it with plastic, isolating it from water and oxygen and preventing toxic chemicals from leaching into nearby water bodies. Workers could then apply an additional dirt cover to establish vegetation.

Cawley, the Selectboard chair, predicts that the biggest impact on the town at large will be the strain on roads. Residents living on Richardson Road, which skirts the mine, will bear the brunt of the disturbance.

“It’s not a heavily trafficked road, and then you have 50 dump trucks going up there every day, that’s going to be rough,” Cawley said.

The runoff from Elizabeth Mine, which required cleanup similar to what Hathaway said will be needed at Pike Hill, was responsible for 5 miles of streams present on Vermont’s impaired waters list. Now the water there runs clear and has fully recovered.

“If we’re successful like we were at Elizabeth Mine, that would be a great victory,” Hathaway said.

Hathaway, who was involved in the early studies at the site in the 2000s, said he is relieved to be getting back to the project.

“This is why you do this job,” he said. “We’re trying to improve the environment and work closely with the communities, hopefully adding some value to the town as well.”

Cawley is grateful that the EPA is showing up with Elizabeth Mine already under its belt.

“Now we’re excited to see how they get going in Corinth,” he said. Over 40 residents showed up to the first community meeting hosted by the EPA in mid-June.

The next meeting will be at 7 p.m. on July 19 in the Corinth Town Office. Organizers hope to offer a virtual option, but as of now, details are not available.

Further information can be found here.

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