Minnesota Treatment Plants Grapple With Dioxane

Two water plants in Minnesota are waging a battle against a likely cancer-causing industrial chemical, and their facilities need multimillion-dollar upgrades to fend off the contaminant, which has been detected in 19 municipal water systems in the state.

“The industrial chemical — 1,4 dioxane — comes from the long-closed Twin Cities Army Ammunition Plant (TCAAP) in Arden Hills and only recently emerged as a contaminant. Now it’s showing up in the groundwater supply used by New Brighton and St. Anthony,” the Star Tribune reported.

Dioxane is used in the manufacture of pharmaceuticals, and it is a byproduct in some plastic manufacturing processes, according to the U.S. EPA. The agency labeled dioxane “a likely human carcinogen about four years ago, adding it to a watch list of contaminants to be monitored in public water supplies,” the Star Tribune reported.

It migrates rapidly in groundwater “ahead of other contaminants and does not volatilize rapidly from surface water bodies,” according to the EPA.

Amy Hadiaris, a Minnesota Pollution Control Agency (MPCA) hydrogeologist and manager for the TCAAP Superfund site, explained why the dioxane problem is coming to a head now.

“Two things have happened to make it a concern today: We now have the ability to detect it in the water, and we have additional information about potential health risks,” she said, per the Star Tribune.

Dioxane can be hard for utilities to spot.

“As a result of the limitations in the analytical methods to detect 1,4-dioxane, it has been difficult to identify its occurrence in the environment. The miscibility of 1,4-dioxane in water causes poor purging efficiency and results in high detection limits,” the EPA explained.

St. Anthony Mayor Jerry Faust noted this conundrum.

“Testing technology has become more sophisticated. It’s probably been present the whole time. It’s just there was no diagnostic equipment for the MPCA to test for it.”

Pump-and-treat remediation with ex situ treatment tailored to dioxane is one way to treat the chemical, according to the EPA, along with advanced oxidation processes using hydrogen peroxide with ultraviolet light or ozone in the case of wastewater. Research is underway seeking new ways to treat the chemical.

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