By Wally Kennedy

wkennedy@joplinglobe.com

CARTERVILLE, Mo. — Workers with Snyder Construction Co. began clearing away piles of rock Wednesday at a former mining site along old Route 66 on the west side of Carterville.

The work kicks off a $1.9 million contract with the U.S. Environmental Protection Agency to clean up the mining field, which was abandoned nearly a century ago.

Motorists passing the site might be surprised to see a conveyor belt operating in the work zone. The conveyor belt is not part of the cleanup plan.

Blevins Asphalt, which operates in Joplin and Mount Vernon, purchased a chat pile in the field about three years ago. When the EPA recently announced that it was cleaning up the site, Blevins informed the EPA of its ownership of the small mountain of crushed rock.

“We learned about it in the pre-construction visit. We’ll just have to work around it until they are done,” said Mark Doolan, project manager with the EPA. “It put a kink in our plans, but it’s material we don’t have to handle.”

The EPA permits the use of chat as an aggregate material in the production of asphalt and concrete because the mining waste is encapsulated. The EPA does not permit the dispersal of loose chat on private driveways or on public roads because of the potential release of heavy metals.

The EPA, in this first phase, plans to restore 75 acres on the west side of the city. The project will take about eight months to complete. Eventually, more than 300 acres between Webb City and Carterville will be reclaimed.

The plan

The contract calls for Snyder to dig up mine waste and contaminated soil, and place the materials in abandoned mine pits. The EPA chose the plan after testing the approach a few years ago at a mining pit near Waco.

At the Waco test site, a two-acre pit that was 45 feet deep was filled with 560,000 cubic yards of highly contaminated mine waste. The metal of concern was zinc because it is far more mobile in water than lead.

“This was a worst-case scenario for the whole site,” Doolan said. “The mine wastes were highly contaminated with zinc. We are talking 30,000 parts per million. That’s one of the highest levels of zinc contamination we have found anywhere in the district.”

Before the wastes were moved, water samples were taken from the pit and from monitoring wells around the pit. After the pit was filled, a monitoring well was placed in the center of the pit. The levels of zinc in the well spiked for about a month or so after the pit had been filled.

“It went really high for a month, but now it’s less than before we filled the pit,” Doolan said. “The monitoring wells around the pit went up and then went down. The change did not amount to anything.”