PHOENIX (KVOA) - The Arizona Department of Environmental Quality announced Thursday that it has begun field work to address the Perfluorinated Alkyl Substances (PFAS) threat to the City of Tucson’s drinking water supply.
It said work is well underway and continues moving ahead. ADEQ said it has dedicated $3.3 million from its limited Water Quality Assurance Revolving Fund to stop PFAS from impacting key Tucson drinking water sources. ADEQ’s Central Tucson PFAS Project is focused on delineating and capturing PFAS-contaminated groundwater to prevent it from impacting additional drinking water production wells.
According to ADEQ, multiple and distinct areas of groundwater contaminated with PFAS above the U.S. Environmental Protection Agency’s Health Advisory Level have been identified in Tucson. Some of this contamination is encroaching on Tucson Water’s backup drinking water supply wells. It said 18 Tucson Water backup drinking water supply wells have been shut down due to PFAS, resulting in a loss of 10 percent system well capacity.
Tucson Water estimates an associated unfunded future replacement cost for these wells at tens of millions of dollars. Without this additional work by ADEQ, more drinking water supply wells in Tucson could be impacted.
ADEQ said Tucson Water identified PFAS originating from Davis Monthan Air Force Base as a priority threat to the City’s water supply. Although the U.S. Department of Defense is actively investigating sources of PFAS contamination from federal facilities, Tucson Water requested ADEQ’s assistance to expedite action, concurrent with the ongoing federal environmental investigation, to prevent additional well impacts in the short-term.
Located to the north of DMAFB, the backup wells were disconnected from the drinking water distribution system in 2018 when PFAS was first detected to ensure that the public water supply remains safe to drink. While Colorado River water is the primary drinking water source for Tucson today, the aquifer in the Central Basin is critical as an alternate drinking water supply for over 600,000 residents in the future.
"Ever since the initial detection of PFAS in this portion of our aquifer, we have been fortunate to have collaborated with the various agencies and organizations working to address this problem. We are grateful to the State of Arizona and ADEQ as they move forward with the process of drilling monitoring wells to help understand the extent of the contamination and identify possible solutions to keep it from spreading further," said Deputy Director of Tucson Water John Kmiec.
“The security and availability of healthy drinking water for the second largest metropolitan area in Arizona is critical,” said ADEQ Waste Program Division Director Laura Malone. “That’s why ADEQ has prioritized limited WQARF funding to proactively protect Tucson’s water supply from additional impacts from PFAS. WQARF is uniquely designed to allow ADEQ to take swift action and immediately provide mitigation needs for Tucson residents.”
ADEQ said its first step was to complete a Central Tucson PFAS Project Work Plan in June 2020. The CTPP Work Plan calls for installation of a network of up to 16 new groundwater monitoring wells. Additional work includes collecting and analyzing soil, sediment and groundwater data to determine the location and extent of two PFAS compounds.
ADEQ initiated field work for the CTPP in October 2020, and said it will use the data collected to design and construct a remedy to prevent movement of the PFAS-impacted groundwater. Installing a wellhead treatment system near the PFAS-source area will both remove PFAS and begin the process of containment. ADEQ said it has already initiated design, planning and permitting for a field pilot test at a City of Tucson supply well to be conducted in early summer 2021. ADEQ is keeping residents and businesses in the area of the field work informed and is coordinating closely with Tucson Water.
According to ADEQ, residents and businesses who receive their drinking water from Tucson Water are continuing to receive drinking water that not only meets EPA’s HAL for PFAS, but also meets Tucson Water’s more conservative internal operating targets for PFAS.