Oct. 1 2018 11:33 AM

Possible cancer-causing substance found in water coming from treatment plant.

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A water treatment plant in Tucson, Arizona had to be shut down following the discovery that it had been sending contaminated water to thousands of downtown, west and north side residents, according to a story published in the Arizona Daily Star and posted on the Tucson.com website.

The water coming out of the treatment plant had been tainted with perfluorinated chemicals, also known as PFAS compounds. The plant had been built and later upgraded to treat the toxic solvents trichloroethylene (TCE) and 1,4-dioxane but not PFAS.

PFAS, a family of compounds used in firefighting foam, is also found in nonstick frying pans, polishes, carpets, waxes, paints, and industrial processes. They don’t easily break down in the environment, remain in the body a long time, and have been linked to a long list of illnesses, including cancer.

Utility officials had thought that uncontaminated water was coming out of the plant and had been sampling water at a point thought to be connected to it. They discovered that the plant was actually getting water from other sources.

Although the levels of the chemicals found in the water, which was pumped to some 60,000 Tucson residents, were lower than the recommended maximum by EPA health advisories, they were higher than a recently released federal study says they should be.

Officials say they don’t know how long the contaminated water had been served to customers. The utility decided to sample the area this year because it was finding the chemicals in other locations, forcing it to shut down wells, says Tucson Water Director Tim Thomure.

The plant was put back online Sept. 17 after being closed for more than three weeks while the utility took several short-term measures to reduce contamination levels.

Tucson Water has since taken new samples in the area where the treatment plant’s water is delivered and expects they’ll contain significantly lower levels of the contaminants.

The utility’s reliance on the wrong sampling point drew sharp criticism from City Council members Steve Kozachik and Regina Romero.

Kozachik called the mistake “cavalier,” given the city’s longstanding history with water pollution and the community’s sensitivity to it, said Kozachik.

“Is it embarrassing? Yeah,” acknowledged Jeff Biggs, Tucson Water’s administrator for strategic initiatives. But, he said, the city had questioned the discrepancy in the pollution levels it was finding and reacted immediately once it learned of the mistake.

The contaminated water had gone through a water-treatment plant known as the Tucson Airport Remediation Project, commonly known as the TARP plant. It was first built in 1994 to remove the once-common industrial solvent trichloroethylene from polluted groundwater — a solvent that various aircraft-related industries had dumped into the ground from the late 1940s to the mid-1970s.

In 2014, the plant was upgraded to remove 1,4-dioxane, an industrial stabilizing agent, from that same groundwater. The pollutant was discovered to be in it as far back as 2002.

The plant’s construction was a result of a consent agreement that the city signed with the U.S. Environmental Protection Agency and other parties to clean up the water, long after the TCE was first discovered there in 1981.

Tucson Water had thought the plant had been removing the PFAS along with those other pollutants, partially because the treatment plant contains granulated carbon materials thought to be good at removing these compounds from water.