Arsenic found in buried ditch

Arsenic contamination in concentrations much higher than the "action level" that trigger a cleanup has been discovered in a now-buried ditch between Copperton and Magna.

Federal, state and Kennecott Utah Copper officials are working to clean up the material. Where it remains buried, it poses no threat to the public, say experts. But Kennecott promises to help with the cost of clearing contamination from private land.

The Bingham-Magna Ditch was used in the 1930s to take wastewater from the Utah Copper Co. operations at Copperton to an impoundment at Magna. After the ditch was filled in around 1937, the Utah Copper Co. and the impoundment were acquired by Kennecott.

According to Kennecott, it began near Copperton, went east to around 7000 West, and then north in what are now West Jordan, West Valley, Kearns and Magna.

Recent excavation by a new development along the right-of-way exposed the ditch and its layer of bright-red sediment, which contains arsenic. The ditch bottom is about two feet to four feet below the surface of the land, and the sediment is the bottom 2 inches to four inches of that.

Kelley Payne, Kennecott project manager for remediation, said the sediment checked so far registered arsenic at 1,500 parts per million to 3,000 ppm. The level that causes a clean-up is 100 ppm, he said.

"These are sediments we're looking to clean up," he said. He added, "Where they're buried there's no real risk of exposure. If somebody digs into them there's a potential risk."

The ditch once disposed of wastewater from a plant built near Copperton to extract copper from mine water. The extraction process used iron, which attracted arsenic, and arsenic-contaminated sediments settled to the ditch's bottom.

"We're working with the developers to make sure that the area is cleaned up," said Dianne Nielson, executive director of the Utah Division of Environmental Quality. Speaking of soil already uncovered, she added, "Clearly the contaminated soils need to be removed."

Nielson said the state has worked before with property owners with similar kinds of concerns to make sure the public is safe.

"I think we understand the extent of its range," she said. "It's now just a matter of working through and making sure the appropriate actions are taken so people don't have to worry about the contaminated soil."