City to receive $25M to improve water cleanup in Tucson

Tucson Water will get $25 million from the state later this year to improve its south-side water treatment plant's ability to remove potentially cancer-causing PFAS compounds from contaminated groundwater flowing into it.

The money will be spent on a treatment process using as yet undecided technology to remove the PFAS compounds, Tucson Water officials said last week. The new facility will be installed at the site of the Tucson Airport Remediation Project, which has treated polluted south-side groundwater since 1994.

While utility officials hope to cut an agreement with the state in the first months of 2023 for releases of the money to Tucson, it will likely take at least three years to get a new treatment facility online at the plant. When in operation, it will be a major improvement over the current treatment process that uses granular activated carbon filtering to remove the PFAS, officials say.

That's because the carbon filtration method, while it does work, was not designed to remove PFAS compounds from the water, utility officials have said. The new treatment facility will be designed explicitly for PFAS removal.

ADEQ and Tucson Water officials announced the $25 million award to the utility just before Christmas. The money will come through the state from funds appropriated by the federal American Rescue Plan Act.

“I am grateful for this collaboration (with ADEQ officials) to continue protecting our water security,” said Tucson Mayor Regina Romero, in a news release announcing the $25 million award to the city. “We are all too aware of the painful history of water contamination in our region, especially those impacting disadvantaged communities. There is much work to do to clean up PFAS throughout the Tucson region, and this is an important step forward."

While this water is not used for drinking today, officials have said it is important to get it as clean as possible, in case it is needed to replace Central Arizona Project water from the Colorado River. Its deliveries to Tucson could be curtailed in the coming years due to the Colorado's shrinking supplies, triggered by drought and long-term climate change.

“This funding will help Tucson Water secure Tucson’s water supply for future generations,” said Gov. Doug Ducey in the joint city-state news release. “Every source of water in Arizona is critical as we face drought conditions and the risk of a drier future.”

But while this money is welcome, it's a "drop in the bucket" compared to what's needed to clean PFAS from city wells lying on the south side, the southeast side near Davis-Monthan Air Force Base, the northwest side in the Continental Ranch area and elsewhere, said Vice Mayor Steve Kozachik.

"Twenty-five million dollars is nice, but everybody who has studied this stuff knows that’s not going to be enough in the long run or even the short run," and it will take hundreds of millions of dollars to get the community-wide PFAS contamination addressed, said Kozachik, the most outspoken councilman on the PFAS issue.

The south-side plant, commonly known as TARP, has successfully removed two other toxic chemicals from the groundwater entering it. They are trichloroethylene and 1-4 dioxane, both known or likely cancer-causing substances.

But the PFAS compounds, which have possible links to kidney and testicular cancer, have been more difficult to treat because the original TARP plant wasn't designed to treat them. Concentrations of PFAS increased significantly in south-side groundwater from 2017 into the early 2020s.

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That caused Tucson Water officials to shut the TARP plant down for a few months starting in June 2021, out of concern that the rising PFAS levels would overload the facility's carbon treatment methods. The plant was reopened that December, after the utility, using $2 million in state funds, built a pipeline to take the treated water for discharge into the neighboring Santa Cruz River near Interstate 10 and Irvington Road.

The plant continues treating contaminated water for PFAS. It treated 440.5 million gallons of groundwater for release into the Santa Cruz during the third quarter of 2022, ending in September, said a recent memo from Pima County Administrator Jan Lesher. The treated water's PFAS concentrations are so low that they cannot be detected by the utility's equipment, officials have said.

But officials continue to be concerned that the PFAS compounds could ultimately overload the carbon filtration system.

The new treatment plant's goal will also be "to effectively remove PFAS from the incoming water to the TARP facility," the utility said in a statement. That way, the current granulated activated carbon treatment can be used to help remove  TCE and dioxane from the water, as it had done before.

That process essentially destroys TCE and 1-4 dioxane by adding hydrogen peroxide to the water as it comes into the plant from city wells. The peroxide oxidizes the water's chemical compounds, and the oxygenated water is passed by ultraviolet light. It breaks apart the oxygenated compounds. Then, the granular activated carbon "quenches" any residual hydrogen peroxide molecules — essentially decomposing the peroxide.

“The investment in the new treatment process will allow the original TARP remedy to continue on without the threat of having to turn off the plant because of the inability to treat for PFAS contamination,” said Tucson Water Director John Kmiec said in the news release announcing the $25 million award.

The plant's technology will most likely employ a solid adsorption material, to which PFAS compounds in water would attach. That method can handle higher concentrations than granular activated carbon filtration, the utility said in its statement.

The current, granular activated carbon treatment process is inefficient and costly as PFAS concentrations in the groundwater increase, the utility said in its statement. While that method is acceptable for treating low concentrations of PFAS, adsorption "will provide a more efficient treatment process as we expect the PFAS concentrations to continue to increase over time," the utility said.

"We are anticipating it will take at least three years to design, construct and put a facility on line," the utility said. "Until a detailed design and engineering estimate is conducted, this estimate is preliminary."

In the news release announcing the $25 million award to Tucson, ADEQ Director Misael Cabrera said, “I am so grateful that the state was able to prioritize this critical project to avoid failure of a Superfund remedy in an environmental justice area of Tucson."