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“The sudden spike in PFAS contamination in wells serving a south-side water treatment plant is a product of humans and nature, experts say.

Tucson Water could well have increased the buildup of these chemicals in the wells by pumping tainted water out of the wells and toward the plant, said one scientist and a city official. The pumping can pull more heavily contaminated water lying south of those wells into the wells, boosting their PFAS concentrations.

At the same time, other experts say some PFAS compounds, unlike the trichlororethylene that’s been in the south-side’s aquifer for many decades, can move quickly in groundwater, rather than attaching to soil particles that store water in the underground aquifer.

Just the fact that it happened is not that big a surprise to some officials, since Assistant City Manager Tim Thomure says, ‘We see that type of change occur routinely with PFAS.’

But the latest increases, ranging up to 700% since 2017, have now triggered Tucson Water’s decision to shut the plant down indefinitely. If concentrations keep increasing, they’ll overwhelm the Tucson Airport Remediation Project plant’s ability to treat PFAS at all, officials said last week…”