Saturday, February 4, 2023

Report: Concentration of 1,4-dioxane detected in water highest at Sweeney Treatment since 2015

The Cape Fear Public Utility Authority has detected high levels of 1,4-dioxane in the Cape Fear River (Port City Daily photo | Benjamin Schachtman)
The Cape Fear Public Utility Authority has detected high levels of 1,4-dioxane in the Cape Fear River. (Port City Daily photo | Benjamin Schachtman)

WILMINGTON — The Cape Fear Public Utility Authority has detected increased levels of chemicals found in industrial solvents in raw water from the Cape Fear River — the drinking water supply for most of the tri-county area.

Now, CFPUA is consulting with the N.C. Department of Environmental Quality.

“CFPUA periodically tests raw water for 1,4-dioxane, which is used in industrial solvents and for several years has been detected in the Cape Fear and other North Carolina surface waters. Its presence in the Cape Fear River results from upstream discharges,” according to a CFPUA press release.

CFPUA’s water treatment plants do manage to reduce levels of 1,4-dioxane in drinking water but do not completely remove it.

“The Sweeney Water Treatment Plant, which treats water from the Cape Fear River, is one of the few water utilities in North Carolina equipped to significantly reduce 1,4-dioxane in water. This results from past investments in ozone and granular activated carbon filters operated in biological mode, technologies that typically result in average removal rates for 1,4-dioxane of 67 percent,” according to the release.

“The latest results, which became available this week, showed concentrations of 1,4-dioxane of 2.2 parts per billion (ppb) in raw (untreated) water on July 1 and 0.54 ppb in finished (treated) water at Sweeney on July 2. The concentration of 1,4-dioxane detected in raw water is the highest detected at Sweeney since 2015,” the release continues.

This is the second time this year CFPUA has noticed a rise in the levels.

 “In March we reported concentrations 1.8 ppb in raw water on February 13 and 0.54 ppb in finished water treated at Sweeney on February 14. These results and others are posted on CFPUA’s website. CFPUA has shared these results with its regulatory partners at NCDEQ,” according to the release.

So what can be done and what are the risks? Well, the federal government has not set a maximum contaminant level for 1,4-dioxane.

A risk assessment by the U.S. Environmental Protection Agency has indicated that a concentration of 0.35 parts per billion in drinking water consumed over a lifetime would be expected to cause no more than one additional case of cancer in 1 million people. It should be noted that these results are insufficient to indicate a trend. Over the last few years, 1,4-dioxane levels in finished water have routinely been below the EPA assessment level,” according to the release.

“Importantly, CFPUA and the community it serves is affected by the actions of dischargers upriver: Higher levels of 1,4-dioxane resulting from upriver discharges will affect the levels in finished water,” the release concludes.

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