April 20, 2024

DEP targets Blue Hill copper mine Metals continue leaching in water near closed site

BLUE HILL – It’s been almost 25 years since Kerramerican Inc. ended operations at its copper and zinc mine off Route 15.

Most of the mine site, which covered between 75 and 100 acres, is now hidden by vegetation. All that remains at the main site are a few concrete foundations and a lot of broken rock. A monitoring well marks the general area where the main mine shaft went down about 1,000 feet, providing access to the rich veins of copper and zinc ore that were mined there.

The mine, which had operated between 1971 and 1977, was officially closed under an agreement with the Maine Department of Environmental Protection in 1981. But the operation continues to have an impact on the area.

Inspections of the site during the past decade have shown that metals leaching from the site off Route 15 have entered the surface water and traveled off the mine site to surrounding areas.

Although there has been no evidence that the leachate has posed a danger to humans or to the groundwater in the area, state officials continue to require monitoring in and around the site as part of the process of closing the mine using current state standards.

“There’s no intention to mine there again,” said Randy King, an environmental specialist with the DEP. “This process will close it down for good.”

On Friday, King joined John Stroiazzo, project manager for Kerramerican, at the site to inspect the ongoing process of drilling monitoring wells. Crews were drilling two new wells at a site off the Grindleville Road near the mine site, bringing to 17 the number of monitoring wells on and around the mine site.

Earlier this spring, the department conducted tests at homes in the area that have drilled wells. The results showed that there had been no impact on the well water from the mine, King said.

Establishing the monitoring wells, which began two years ago, is part of the assessment and planning process in an effort to reclose the site to latest standards, King said. The DEP is overseeing the process.

Kerramerican and the DEP plan to hold a public meeting at 7 p.m. Wednesday, June 19, to review past activities at the mine and to discuss ongoing environmental investigations and the steps being planned to properly close the site.

Since the site was closed, there has been very little maintenance at the mine, according to King. In 1994, an inspection by the department’s land bureau determined that some of the soil covering waste metal deposits had eroded to expose waste tailings, or byproducts.Based on that discovery, the bureau recommended the site for further evaluation, King said. The mine was in the process of being certified as a federal Superfund cleanup site when the company opted to work with the DEP under the state’s uncontrolled site program.

“Kerramerican stepped forward and volunteered to remediate the site under arrangement with the DEP and the state of Maine,” King said.

The problem with the site is that metals leaching from the site have gotten into the surface water and are affecting the environment around the mine. Earlier studies have indicated that metals, such arsenic, cadmium chromium, copper, iron, lead, mercury, nickel, silver and zinc, have been found in the surface water pathway as far away as Salt Pond, several miles away from the mine site.

The chief problem, however, appears to be high levels of zinc, according to Stroiazzo.

For the past two years, Kerramerican has conducted studies at and around the site which have indicated that much of the leaching is coming from the main mining site adjacent to Second Pond.

The mine site once consisted of a variety of processing and storage buildings located around the mine shaft and two tunnels. The shaft went down about 1,000 feet to reach the main veins of copper and zinc, the main lodes of which were located directly under Second Pond. At the height of the operation in 1977, there were reportedly about eight miles of underground roads serving the mine.

In the process of reaching the rich veins in the mine, miners brought up broken rock that, although containing some elements, was not as rich as the main vein and not worth processing. That broken, “waste rock” was discarded at the site, some of it being used to create roads around the site.

Although the main site was partially covered when the site was closed in 1981, Stroiazzo said, air and water still has been able to get into those areas of waste rock. The water has leached materials from the rock and carried them down through the layers, eventually entering the environment mainly through surface water downgrade.

“We think we’ve got a pretty good idea of what the situation is here,” Stroiazzo said. “We think that if we can cover the mine area, we can reduce the problem by about 80 percent.”

There still needs to be some additional assessment of the entire area, King said, but the company has conducted computer models for closing the mine site, and already is developing a plan to “recap” the mine area using a thick layer of clay. The final closure plan will require DEP approval before the actual work can begin.

If the DEP approves a plan this summer, preliminary work could begin in the fall. In all, Stroiazzo said, it will take three construction seasons to complete the closure.

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