In this Aug. 19, 2019, file photo, abandoned equipment rests among weeds outside the Elizabeth Mine in Strafford, Vermont. Credit: Wilson Ring / AP

STRAFFORD, Vermont — A final tally of the cost of cleaning up the long-abandoned Elizabeth copper mine in the Vermont town of Strafford came in more than four times the original estimate, the Environmental Protection Agency says.

The Valley News reported that when the Superfund project to clean up the mine began in 2002, its estimated cost, in today’s dollars, was $25 million. When the cleanup was completed earlier this year, the EPA final price tag came in at $103 million.

Ed Hathaway, the EPA’s Elizabeth Mine project manager, said “cost increases are very common” in the Superfund program.

“We’re not building a house. We essentially are unwrapping the site as we clean it up. … As we excavate and as we do work, we uncover more of the challenges,” Hathaway said.

In 2001, the EPA designated the abandoned 250-acre copper mine a Superfund site. Acid- and metal-contaminated water from the site contaminated nearby streams.

Copper ore was first discovered in the area in the 1790s. Mining operations waxed and waned over the decades with economic conditions.

The mine closed for good in 1958. The closure left behind 7,800 feet of tunnels; abandoned buildings; equipment; huge piles of rock, known as tailings; and other mining debris.

After the mine closed, contaminated water leached from waste rock and tailings into nearby streams, endangering animals and homes nearby.

During the nearly 20-year cleanup 400,000 cubic yards of waste rock was moved and contaminated areas capped. Engineers rerouted the Copperas Brook and designed a drainage system that has reduced what comes out of the tailings to a relative trickle.

After the work on the cap was finished, about 20,000 solar panels capable of generating enough power for an estimated 1,300 Vermont homes were installed as a way to find a use for part of the site.

The EPA has estimated the amount of copper flowing into the nearby Ompompanoosuc River has fallen 99 percent, while the concentration of iron dropped 95 percent, prompting environmental officials to remove the river from the list of Vermont waterways deemed too impaired to support aquatic life.

The Vermont Agency of Natural Resources will take over control of the property, though the EPA will continue to offer technical assistance and conduct reviews every five years. The property is still privately owned.