EPA#: AZD980737530

Superfund National Priority List (NPL) Placement: Sept. 8, 1983

Location

The Tucson International Airport Area (TIAA) Superfund Site covers an area of approximately 7,500 acres and is divided into seven separate project areas. The project areas include: Air Force Plant 44, Tucson Airport Remediation Project (TARP), Texas Instruments (formerly Burr-Brown), Morris Air National Guard, Airport Property, West Plume B, and West-Cap. 

The TARP project area is in the northwestern portion of the TIAA site and is bounded on the east by Nogales Highway (Route 89 and on the west by Interstate 19.) 

The TARP groundwater plume extends from Los Reales Road northward to just past Irvington Road | View Map >

Contaminants of Concern (COCs)

Groundwater | Volatile organic compounds (VOCs), primarily trichloroethylene (TCE). Other contaminants in the groundwater include 1,4-dioxane and per- and polyfluoroalkyl substances (PFAS).

The City of Tucson is the main municipal water provider at this site. All municipal wells in the area that were contaminated with TCE have been shut down. The nature and extent of PFAS contamination is currently under investigation.

If you are drinking water from a private well within the boundaries of the site, we encourage you to test the well. 

Not sure what to test for? | Learn More >

COCs at the site may change as new data become available.

Action Taken

Groundwater remediation at TARP began in 1994 when Tucson Water began to operate the remediation system which consisted of a South Well Field of five extraction wells, a North Well Field of four extraction wells, and a groundwater treatment plant (GWTP). Contaminated groundwater initially was treated at the GWTP using packed column aeration, however, in 2014, an advanced oxidation process (AOP) system started operation to remove TCE and 1,4-dioxane from the groundwater. The AOP system includes ultra-violet light reactors, peroxide storage/feed equipment, and a granular activated carbon (GAC) tank for peroxide quenching. In 2024 an additional extraction well (R-127A) was added to extract groundwater from an area of high TCE contamination. Between June 2021 and November 2021, the TARP system was shut down. The system was restarted following construction of a discharge pipeline to the Santa Cruz River. In 2023, following construction of a pipeline to the Recycle Water System (RWS), the TARP GWTP could discharge to both the Santa Cruz River and the RWS. Recently Tucson Water installed ion exchange vessels for the removal of PFAS.

In 2023 the U.S. Environmental Protection Agency (EPA) issued an Interim Record of Decision to formalize AOP as the treatment method to remove TCE and 1,4-dioxane at the TARP GWTP and eliminate the packed columns.

In 2026 an Explanation of Significant Differences to the 2023 Interim Record of Decision Amendment for Area A North of Los Reales Road Treatment for Per- and Polyfluoroalkyl Substances was published.

Status

The TARP system continues to remove TCE- and 1,4-dioxane-contaminated groundwater at the TIAA Superfund Site. Contaminated groundwater is extracted from five extraction wells located near the toe of the TCE plume (northern well field)  and piped to the TARP GWTP. The southern well fields have been taken offline. The TARP system extracts and treats groundwater at a rate of approximately 4,500 gallons per minute. Treated water from the TARP GWTP is delivered to both the Santa Cruz River and the RWS.

Water level and water quality data are used to evaluate the performance of the existing remediation well fields for capturing groundwater contamination. These data indicate that the TARP remediation system is meeting compliance requirements, and the TARP GWTP treatment plant shows consistent performance in removal of VOCs, 1,4-dioxane and PFAS. In 2026, Tucson Water is operating an ion exchange vessel for the removal of PFAS.

This site is subject to programmatic five-year reviews and the next review will be conducted in 2028.

Learn More

Learn more about this Superfund site on the EPA website | View Site >