Tony Davis 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.
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. 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.
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.
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.
"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."