DNR reviews handling of patching material at Douglas County highway garage

The Wisconsin Department of Natural Resources is reviewing how Douglas County handled a water-petroleum mixture at the county garage in Hawthorne.

“I don’t think it is anything that constitutes an environmental risk or threat, but it is something that required clean-up,” DNR hydro-geologist Erin Endsley said. “It is cleaned up at this point.”

Douglas County Highway Supervisor Paul Halverson said county workers did nothing wrong when they poured the material in a trench by the garage. The material is a water-based asphalt emulsion that is sprayed between layers of asphalt to help them bond or on gravel shoulders to help stabilize the gravel.

“It’s legal to spread it on the shoulder of highways,” he said. “It’s not a banned substance or anything like that. It is something that is intended to be sprayed. As soon as the water in it evaporates, it sets right up. It doesn’t soak in.”

A load of the material had been stored in a truck overwinter and was no longer suitable for use on roads, Halverson said. Most of the load was sprayed on a stockpile of blacktop rubble waiting to be recycled. But some of the load at the bottom of the tank was too dense to be pumped. It was this material that workers drained into the trench.

“As soon as the water evaporates, that sets up hard,” Halverson said. “Then we would excavate that material and mix it into the pile.”

The DNR became involved after receiving a complaint earlier this week. Endsley visited the site Wednesday to ensure that the county had removed the material from the trench. She said the trench was about 30 feet long, 3 feet wide and 2 feet deep. It would have been smaller before the material was removed, she said.

John Sager, the DNR’s northern regional spill coordinator, confirmed that the state was investigating the incident as a spill.

“It was not being used for its intended use; it was all concentrated in one place,” he said. “That is why we’re considering it a spill.”

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