Tucson Airport Remediation Project
Mobilizing Against Groundwater Pollution
In 1981, Tucson Water shut down eleven groundwater wells in response to the detection of trichloroethylene (TCE) in the groundwater supplies near Tucson International Airport. The release of TCE was a result of industrial and defense related practices on or near the Tucson International Airport property that took place from the 1940s through the 1970s. The U.S. Environmental Protection Agency (EPA) responded to the discovery of TCE by adding the site to its Superfund list on September 9th, 1983.
Community Collaboration
A coordinated effort to protect water users from exposure to TCE and restore Tucson’s aquifer was addressed by the mobilization of the Unified Community Advisory Board (UCAB) in 1995.
The EPA, Tucson Water, Tucson Airport Authority, Air National Guard, and Air Force continue to meet quarterly to keep the community informed with ongoing updates on groundwater remediation at the Tucson Airport Remediation Project (TARP).
View Tucson Water's Quarterly Status Report(PDF, 1MB)
History of Investments
In September of 1994, Tucson Water completed construction of the TARP Water Treatment Plant, which included:
- Nine remediation wells
- Associated pipelines
- A treatment facility
The purpose of the project was to remediate the portion of the aquifer contaminated by TCE and prevent migration of TCE into Tucson’s central wellfield. Treated water, free from TCE, was added to the potable water system.
Responding to New Contaminants
In 2011, the EPA issued a new, unenforced health advisory for 1,4-dioxane at 0.35 parts per billion. With proactive direction from City of Tucson Mayor and Council, Tucson Water designed and constructed the Advanced Oxidation Process (AOP) Treatment Facility.
This facility began effectively removing 1,4-dioxane and TCE from the aquifer for potable use in February 2014. The AOP project received five awards for the design and impact of the facility from organizations like the American Academy of Environmental Engineers and Scientists.
TARP/AOP Plant Update
Tucson has been successfully removing per- and polyfluoroalkyl substances (PFAS) at TARP wells below detection limits. However, rising PFAS levels increased the risk of the chemicals entering the drinking water system.
To protect customers, treated water from TARP was removed from the potable system in 2021.
Remediation of TCE and 1,4-dioxane continued after an emergency outfall to the Santa Cruz River was built. The outfall was funded by the Arizona Department of Environmental Quality (ADEQ).
In 2023, Tucson Water connected the remediated water from TARP to the reclaimed water system. This ensured the water would be used beneficially and allowed TARP to operate in its intended capacity which was to remediate TCE and 1,4-dioxane.
2021 News Release: Tucson Water will suspend operations of TARP treatment facility
Forever Chemicals (PFAS)
Investing in Ion Exchange
The TARP/AOP facility was originally designed to treat for 1,4-dioxane and TCE, not PFAS.
Some treatment methods, such as the use of granular activated carbon, have been successfully used to remove PFAS but at lower efficiency and higher cost.
To address this, ADEQ allocated $25 million to Tucson Water to build a new PFAS pretreatment system to remove PFAS before entering the TARP Water Treatment Plant.
The system uses ion exchange resin, proven technology also used since 2021, at the Central Tucson PFAS Project.
These facility upgrades will significantly reduce operation and maintenance costs, provide an additional PFAS barrier, allow the UV/AOP process to fulfill its originally intended purpose of treating for TCE and 1,4-dioxane, and increase the overall treatment capacity.
Construction began in January 2025, and the facility is anticipated to be online in late summer of 2026.
The Price of Remediation
The City of Tucson | Tucson Water responded swiftly to water quality challenges at the Tucson Airport Remediation Project. Remediating groundwater protects Tucsonans and preserves our limited water resources. The cost to maintain and operate remediation for TCE is reimbursed monthly by Tucson International Airport. The utility is now working to create cost-sharing agreements for 1,4-dioxane and PFAS — so polluters, not the public, bear the financial burden.