Superfund Information Systems: Site Profile

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The 10-square-mile Tucson International Airport Area site is located in and next to Tucson, Arizona. The site includes the Tucson International Airport, portions of the Tohono O'Odham Indian Reservation (San Xavier District), residential areas of Tucson and South Tucson, and the Air Force Plant #44 Raytheon Missile Systems Company (AFP44). Former aircraft and electronics manufacturing activities, fire drill training activities, and unlined landfills contaminated groundwater and soil. Cleanup, operation and maintenance activities, and monitoring are ongoing.

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What Is Being Done to Clean Up the Site?

The site is being addressed through federal, state, local and potentially responsible party (PRP) actions.

EPA has conducted one five-year review of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review concluded that response actions at the site are in accordance with the remedy selected by EPA and that the remedy continues to be protective of human health and the environment in the short term. Continued protectiveness of the remedy requires vapor intrusion assessments.

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What Is the Current Site Status?

Treatment technologies at the site have removed 130,000 pounds of volatile organic compounds (VOCs), 100,000 tons of metals and 10,000 tons of PCB from soils and groundwater. Groundwater cleanup actions are ongoing.

The site consists of seven separate project areas.

Remedy Selected

Tucson Airport Remediation Project: The long-term remedy includes pumping and air stripping contaminated groundwater, followed by discharging treated water in the municipal water supply.

Texas Instruments: The long-term remedy includes pumping and air stripping groundwater, reuse of treated water and groundwater monitoring. EPA later updated the remedy to add monitored natural attenuation and institutional controls and to replace pumping and treatment with in-place chemical oxidation. Natural attenuation describes a variety of in-place processes that, under favorable conditions, act without human intervention to reduce the mass, toxicity, mobility, volume or concentration of contaminants in groundwater. Remedial design activities are ongoing.

Arizona Air National Guard: The long-term remedy includes pumping and air stripping groundwater, reusing treated water and monitoring groundwater. EPA later updated the remedy to add monitored natural attenuation and institutional controls and to replace pumping and treatment with in-place chemical oxidation.

Former West-Cap of Arizona Property and West Plume B: The long-term remedy includes pumping and air stripping groundwater, reusing treated water and monitoring groundwater. EPA later updated the remedy to add monitored natural attenuation and institutional controls and to replace pumping and treatment with in-place chemical oxidation. Remedial design activities are ongoing.

1,4-DX at Tucson Airport Remediation Project: Remedial investigation activities are ongoing.

Cleanup Progress

APF44: Since 1987, a pumping and treatment system has cleaned groundwater. Soil cleanup activities removed 100,000 tons of metal-contaminated soils and sludges. Metal soils cleanup finished in 2001. Ongoing soils remediation focuses on pilot testing for in-place treatment of subsurface soils that may be contaminating groundwater and improving the efficiency of older extraction wells.

Tucson Airport Remediation Project: Treatment began in 1994 and has removed over 3,200 pounds of VOCs. The system will remain in operation until at least 2025.

Arizona Air National Guard: A pumping and treatment system operated from 1997 to 2012. Remedial design activities for the in-place chemical oxidation system are ongoing. A soil vapor extraction system began operating in 1997 and removed 64 pounds of VOCs. Soils cleanup finished in 1998.

Airport Property: EPA has required the hydraulic containment of highly contaminated groundwater in the aquifer. The rest of the water will be potable after cleanup activities. Construction of a groundwater treatment plant finished in 2007. Removal actions, or short-term cleanups, of soils removed over 10,000 tons of VOC and polychlorinated biphenyl (PCB)-contaminated soil. Cleanup finished in 2012. Landfill remedy activities finished in 2013.

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EPA’s Involvement at the Site

At least 20 facilities have operated at the site since 1942, including aircraft and electronics facilities, fire drill training areas and unlined landfills. Industrial use and disposal of metals, chlorinated solvents and other wastes began in 1942 at facilities on the western portion of Tucson Airport property. This was followed by large-scale waste disposal at the nearby APF44 facility during the 1950s.

In the past, the APFF facility used TCE as a metal degreaser and chromium in electroplating. Electronic circuit board manufacturing, parts degreasing and metal plating shops were the primary hazardous waste-generating operations. Hazardous substances generated by plant activities included spent VOCs (TCE, 1,1-DCE and trichloroethane, or TCA), alcohols, methyl ethyl ketone (MEK), and other solvents, used oil and lubricants, waste paint and sludges, and industrial wastewater treatment residue containing metals such as chromium, cadmium and cyanide. Wastewater and spent solvents were discharged into unlined ditches or disposed of in waste pits and ponds. During storm events, surface water runoff from AFP44 property flowed onto the San Xavier Reservation.

Beginning in 1976, lined wastewater holding ponds were constructed to receive wastewater discharges. By 1987, 35 lined wastewater holding ponds received process wastewater. In 1997, AFP44 completed upgrading its wastewater treatment system, closed its wastewater ponds and has become a non-discharging plant that recycles 97 percent of its water. Current industrial operations include machining, surface preparation, surface coating, metal plating and parts assembly of missiles.

At the Tucson International Airport property (specifically the Airport Three Hangars Area, which was occupied by various defense contractors, including McDonnell Douglas Corporation, Grand Central Corporation and General Dynamics Corporation), chemical use centered on airplane modification and engine part degreasing from 1942 to 1958. During this period, PRPs used and disposed of VOCs on airport property. While TCE was the primary VOC used, other VOCs included methylene chloride, chloroform, carbon tetrachloride and benzene.

Elevated levels of chromium were detected in a Tucson municipal supply well just west of AFP44 in the 1950s. During the same period, residents west of the airport property complained that water from private wells had a foul chemical odor. In 1981, EPA and the City of Tucson conducted groundwater sampling and analysis from municipal water wells on site. The results indicated that there were unsafe levels of TCE contamination in several southside city water wells. Subsequent sampling identified a main plume of groundwater contamination about a half-mile wide and five miles in length. Eleven municipal drinking water wells and several private household wells have been shut down to date because of contamination.

Additional smaller plumes of contamination at the site include the Arizona Air National Guard, Texas Instruments, West Plume B and the former West Cap of Arizona. These sources are located north and northeast of the airport, respectively. Due to poor waste management at these facilities, localized groundwater east of the main contaminant plume is also contaminated.

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