CORINTH — The cleanup of the abandoned Pike Hill Copper Mine, a federal Superfund site, is moving forward with the treatment of contaminated soil and sediment scheduled for late summer and early fall, the Environmental Protection Agency indicated last week.

At a public information session that drew about two dozen people to Corinth Town Hall last week, Ed Hathaway, the EPA’s project manager for Pike Hill, said the “in situ stabilization” portion of the cleanup is estimated to take four to eight weeks.

In situ technologies involve applying “processes to the subsurface to degrade, remove, or immobilize contaminants without removing the bulk soil,” according to the EPA’s website. In situ technologies offer “several benefits, such as addressing deep contamination and generally costing less,” the website said.

By using in situ stabilization methods, which allow for keeping more land in place, Pike Hill’s bat population will be at less risk for displacement or harm, experts at the information session said.

With their population in substantial decline for several decades, partly due to the loss of favorable roosting places, bats are considered an endangered species under federal laws.

The Pike Hill site is prime habitat for bats.

“It’s a cooler site, so it attracts Eastern Small Footed and Big Brown bats,” Alyssa Bennett, a small mammals biologist with the Vermont Fish and Wildlife Department.

Other bats, such as the Little Brown, Tri-Colored, and endangered Northern Long Eared, frequent the caves around the area, making it an important location for a variety of species, Bennett added.

Researchers have tracked bats in the area by banding them and monitoring their calls with ultrasonic recorders. More than 200,000 bat calls have been collected during the study.

Researchers found “bats emerge from April to May, but not many use the mines year ‘round,” said Joshua Guilbert, of the Biodiversity Research Institute, a Portland, Maine-based organization involved in the study. The majority of bats they caught and released for tracking were collected in the fall, Guilbert said.

Researchers also learned that about 190 bats used the Pike Hill site as a hibernation area. In order to protect the area and prevent endangerment, the EPA is working to provide the bat population with artificial roofs, access to clean water and overall forest restoration at the end of the cleanup project.

The copper mine off Richardson Road in Corinth was first listed as a Superfund site in 2004. But a lack of federal money contributed to a backlog of sites, including Pike Hill, in need of cleanup.

Last year, the EPA estimated the Pike Hill cleanup could cost between $18 million and $20 million. Federal taxpayers are responsible for the entire cost of the project.

The Superfund designation is reserved for only the most hazardous polluted areas in the country.

Sulfuric acid leaching from mine waste piles have contaminated surface water and Pike Hill Brook, which empties into the Waits River. The waste piles at the site cover about 15 acres.

Sampling of ground and surface water continues, EPA officials said at the information update session.

Based on the data collected over the past several months, “We’ll continue the same theme… resample the wells on the site, to get a good understanding of the groundwater,” Hathaway, the EPA project manager, said.

Last year’s field investigation looked at 17 sample locations along stream channels as well as tracking possible water pollution near 18 locations where wells were installed.

The cleanup project is about to get much louder.

About 19 acres of woodlands is scheduled to be cleared late this fall and early next winter. The trees are being cut to prepare for the implementation of an underground cell that will store mine waste below a solid natural covering.

After the trees are cut, they’ll be burnt to produce biochar, a solid, rich in carbon and made from organic materials.

When mixed with soil, biochar can help stabilize a mining site and is considered a useful tool in environmental remediation.

A Corinth resident who lives a half mile from the cleanup site shared her concerned about the noise generated by the crushing machine used to make biochar.

The meeting’s panelists acknowledged that the area won’t be as quiet as usual during the several weeks of crushing, but the EPA will “do what we can to mitigate that noise,” Hathaway said.

Some residents also had concerns about increased traffic fueled by large construction vehicles on Richardson Road, which is narrow and unpaved. The EPA estimates that fewer than 200 truck loads of materials will be needed during the initial phase of the cleanup.

The Orange County Copper Belt, a 20-mile stretch of former mining sites that extends from South Strafford to Corinth, ends at Pike Hill. The chain includes Strafford’s Elizabeth Mine, where the EPA largely finished its cleanup work in 2022.

At Pike Hill, copper mining was an off-and-on operation from the mid-1850s to the early 1900s, resulting in the creation of tailing waste on the site.

Although the only remaining site buildings were destroyed by fire in 1960, Pike Hill still features historic foundations from the former mining operations.

“One of our goals is to identify areas where our work will impact (historic areas),” Hathaway said.

Any historic area that cannot be preserved will be documented by archaeologists and researchers prior to its excavation, he said.

Haley Clough can be reached at haley.r.clough@gmail.com.