PIERRE, S.D. (KELO) — South Dakota’s one active gold mine is getting bigger, and so will the amounts of environmental insurance the site must have.

The state Board of Minerals and Environment on Thursday accepted its staff recommendations and increased the bonding amounts for the Coeur Wharf mine, located four miles southwest of Lead.

The mine’s reclamation surety bond total was raised to $72,152,900, an increase of $13,906,800. The post-closure surety bond total was also raised. It is now $42,685,600, an increase of $$4,289,400.

The state board at its July 20 meeting voted unanimously to issue a permit for Wharf to mine what’s known as the Boston expansion area. The company plans to disturb 48 new acres.

That decision triggered the staff’s calculation of the new bond amounts. The additional amounts were issued by Ascot Surety & Casualty. a global company with U.S. offices in New York City and Stamford, Connecticut.

Wharf now has four different companies handling the bonds. Board member Bob Morris of Belle Fourche asked whether the diversity was intentional. Stephanie Kuntz, representing Marsh, a global insurance broker that advises Coeur Mining, said the risk is spread so that no one market is too heavily weighted.

Matt Zietlow, Wharf’s environmental manager, thanked the state board and its staff for their work on the mine expansion and the bond increases. “I think it was an excellent example of a group effort,” Zietlow said.

The board’s chair, Rex Hagg of Rapid City, replied, “I think the process was a good process and I appreciate your work also.”

The mine in 2022 produced 79,768 ounces of gold and 46,067 ounces of silver and paid $4,289,154 of state severance tax.

The expansion is expected to add about three years to the life of the mine, which in 2022 had a workforce of about 250 and a payroll of about $20.7 million, plus nearly $9 million in benefits