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Posted on: March 14, 2019

CFPUA watching recent rise in 1,4-dioxane levels, consulting with NCDEQ

lab sample bottles

CFPUA is working with regulators to understand the cause of a recent instance of increased in levels of 1,4-dioxane in water drawn from the Cape Fear River.

CFPUA has an ongoing, periodic testing program for 1,4-dioxane, which is used in industrial solvents and has been detected in the Cape Fear and other surface waters in North Carolina and nationwide for several years.

A number of investments made at Sweeney Water Treatment Plant, which treats water drawn from the Cape Fear River, make CFPUA one of the few water utilities in North Carolina equipped to significantly reduce 1,4-dioxane in water. Those technologies, ozone and granular activated carbon filters operated in biological mode, typically result in removal rates of 67 percent or better.

The latest results, which became available this week, showed concentrations of 1,4-dioxane of 1.8 parts per billion (ppb) in raw water on February 13 and 0.54 ppb in finished water treated at Sweeney on February 14.

A previous test, conducted in early January, showed concentrations of 0.87 ppb in raw water and 0.5 in finished water. That sample, however, was taken when Sweeney’s ozone treatment was out of service for about a day, so it is not an accurate representation of typical 1,4-dioxane removal at Sweeney. Ozone accounts for about half of the removal rates the plant achieves.

1,4 Dioxane Results for February 2019 sampling

Those results and others are posted on CFPUA’s website.

No federal maximum contaminant level has been established for 1,4-dioxane. A risk assessment by the 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.

Previous to the last results, 1,4-dioxane levels in finished water have routinely been below the EPA assessment level. Higher levels of 1,4-dioxane resulting from upriver discharges will affect the levels in finished water. 

It should be noted that these results are insufficient to indicate a trend and that EPA’s assessment level is for chronic, lifetime consumption.

Even so, CFPUA has been in discussions with its partners at the North Carolina Department of Environmental Quality regarding this data and will continue to monitor concentrations.

The actions of dischargers upriver have an impact on CFPUA’s customers and others who rely on the Cape Fear River for water. Recognizing this, CFPUA works with regulators, researchers, and others to monitor conditions and trends. It also advocates for water regulation and enforcement, including commenting on discharge permits to ensure the community’s interests are considered when upstream, source-control decisions are made.


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