EPA to Cap MT Slag Pile by 2025


A slag pile in Anaconda, Montana, that’s used partially to produce roofing and abrasive blasting material, is slated to be capped after a report was released saying that the dust from the slag could be more dangerous than previously thought.

What’s Going On

A previously unpublished report obtained by the Montana Standard claims that the arsenic in the slag’s dust is about 10 percent more absorbable by the body than the Environmental Protection Agency had thoughts, based on studies done years ago.

The 130-acre pile, located just off Montana Highway 1, is a byproduct of the city’s smelter operation that began in the early 1900s and consists mainly of copper sulfide, copper-iron sulfide and copper-arsenic sulfide.

The report covers test samples that were taken from the pile last fall by EPA contractor CDM Smith. The samples indicated that the arsenic in the slag’s dust is 28.7 percent absorbable in the body.

Previously, the EPA thought it was 18.3 percent absorbable. The study also looked at the lead levels in the slag, but those levels do not appear more hazardous than originally thought.

Although more rigorous testing would need to be done for definitive answers, EPA project manager for Anaconda, Charlie Coleman, said that he does think the information in this report will influence how the cap is designed.

What Now

News outlets reported earlier this month that an agreement had been reached between the state, Anaconda-Deer Lodge County, the EPA and the Atlantic Richfield Company to put a cap—at least 18 inches of clean soil and vegetation—over the pile.

The cap is expected to be complete by 2025.


Tagged categories: Abrasive blasting; Abrasives; EPA; NA; North America; Surface Preparation

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