Pacific Southwest, Region 9: Superfund
Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations
Tucson International Airport Area
EPA #: AZD980737530
Congressional District: 7
The public comment period for the Consent Decree will run from June 22, 2015-July 22, 2015. Click here to view the CD and Federal Register Notice. Comments may be submitted either by e-mail (firstname.lastname@example.org) or by mail
(Assistant Attorney General
P.O. Box 7611
Washington, D.C. 20044-7611).
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Description and History
NPL Listing History
NPL Status: Final
Proposed Date: 12/30/82
Final Date: 09/08/83
The Tucson International Airport Area (TIAA) Superfund site is geographically situated in the northern portion of the Tucson Basin in Pima County, Arizona, south of the intersection of U.S. Interstate Freeways 10 and 19, and includes the south side of the city of Tucson. The Santa Cruz River runs from north to south, about one mile from the western edge of the site. In total, TIAA covers an approximately ten square mile area and includes: the Tucson International Airport; northeastern portions of the Tohono O'Odham Indian Reservation (San Xavier District); residential areas of the Cities of Tucson and South Tucson; and the Air Force Plant #44 Raytheon Missile Systems Company (AFP44).
The site is divided into seven separate project areas: Air Force Plant #44/ Raytheon; Tucson Airport Remediation Project (TARP); Texas Instruments (formerly Burr-Brown Corporation); Air National Guard Base; Airport Property; West Plume B and the former West Cap of Arizona Property. AFP44 is located approximately 15 miles south of downtown Tucson, Arizona and encompasses 1,319 acres of land in Pima County. AFP44 lies south and contiguous to the Tucson International Airport. The Tucson International Airport is owned by the City of Tucson and operated by the Tucson Airport Authority. Prior to 1981, groundwater wells within the TIAA site boundaries provided drinking water to more than 47,000 people.
SITE HISTORY: At least twenty separate facilities have operated at the TIAA area since 1942 including: aircraft and electronics facilities [which discharged waste liquids directly into the soil]; fire drill training areas [where wastes from training operations were left in unlined pits]; and unlined landfills [which received various wastes from several sources]. Minor sources of soil and groundwater contamination were found at the Burr-Brown Corporation, Arizona Air National Guard Base and the former West-Cap of Arizona facilities. Major sources of contamination were found at AFP44 and at the airport property as described below.
Industrial use and disposal of metals, chlorinated solvents and other wastes began in 1942 at facilities located on the western portion of Tucson Airport property. This was followed by large-scale waste disposal at the nearby AFP44 facility during the 1950s.
AFP44 is a government-owned, contractor-operated facility. It is operated under contract by Raytheon Missile Systems Company (formerly known as Hughes Missile Systems Company), under the direct supervision and control of Aeronautical Systems Center, Air Force Material Command, at Wright-Patterson Air Force Base in Dayton, Ohio. Its primary mission is weapons systems manufacturing for the Air Force. Hughes and/or its subsidiaries has operated the plant since its construction in 1951 until it was purchased by Raytheon in 1997.
In the past, the facility used trichlorethylene (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 volatile organic compounds (VOCs) [trichlorethylene (TCE), dichloroethylene (1,1-DCE) and trichloroethane (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, thirty-five lined wastewater holding ponds had been constructed to receive process wastewater. In 1997 AFP44 completed upgrading its wastewater treatment system, closed its wastewater ponds and has become a non-discharging plant which recycles 97% of its water.
Present industrial operations consist of 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 around airplane modification and engine part degreasing from 1942 to 1958. During this period, VOCs were used and disposed of on airport property. While TCE was the primary VOC used, other VOCs included methylene chloride, chloroform, carbon tetrachloride and benzene.
Nature and Extent of the Problem: Although improper waste disposal at TIAA facilities had stopped by the early 1970s, initial indications of groundwater contamination on the south side of Tucson date back to the early 1950s when elevated levels of chromium were detected in a City of Tucson municipal supply well just west of AFP44. During the same time period, residents just 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 city municipal water wells within the TIAA. The results of this investigation revealed that there were unsafe levels of TCE contamination in several south-side City water wells. After identifying the Tucson International Airport Area as a Federal Superfund site in 1982, subsequent sampling identified a main plume of groundwater contamination approximately one-half mile wide and five miles in length. A total of 11 City drinking water wells and several more private household wells have been shut down to date as a result of contamination.
Additional smaller plumes of contamination at the TIAA 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.
Contaminants and Risks
- Soil and Sludges
Contaminants of Concern (COC): The primary COC found at the TIAA site is Trichloroethylene (TCE). Other contaminants of lower concentrations include 1,4 -dioxane, tetrachloroethene (PCE), dichloroethylene (1,1-DCE), chloroform, benzene and chromium.
Health Risks: In response to community requests for a more comprehensive analysis of potential health effects caused by past exposure to TCE, the Agency for Toxic Substances and Disease Registry (ATSDR) carried out a series of significant projects in 1994-96. ATSDR assigned a full-time researcher to the TIAA Superfund site for over one year to collect data and work with a community advisory board. ATSDR issued two detailed reports, The Final Health Survey and the Draft Public Health Assessment, in 1996. Arizona Department of Health Services (ADHS) under an EPA contract, produced a Baseline Human Health Risk Assessment for the TIAA site in 1996. ATSDR issued a final Public Health Assessment for the TIAA site in 2001. In addition, ATSDR conducted community and physician education seminars on TCE-related health effects.
Trichloroethylene (TCE), is a volatile organic compound that has been widely used as an industrial solvent. TCE is a colorless, odorless, liquid. TCE may produce liver injury. Exposures to this compound through inhalation may result in central nervous system depression, including anaesthesia. In the past, TCE has been used as an anesthetic (National Research Council [NRC], 1977). Other effects may include irritation of the mucous membranes of the nose and throat and irritation to the eyes (NRC, 1980). TCE has been classified by the EPA Carcinogen Assessment Group (CAG) as a probable human carcinogen (Group B2) via ingestion (US EPA, 1989). Trichloroethylene is classified as a probable human carcinogen by CAG via inhalation (US EPA, 1989). The Maximum Contaminant Level (MCL) for TCE is 5 parts per billion.
1,4-Dioxane (DX) EPA and the International Agency for Research on Cancer (“IARC”) have determined is a Probable Human Carcinogen (Group 2B), based on sufficient evidence in carcinogenicity in animals. DX has been shown to produce carcinomas of the nasal cavity and liver in multiple strains of rats, liver carcinomas in mice, and gall bladder carcinomas in guinea pigs. The National Institute of Environmental Health Sciences has determined that DX is reasonably anticipated to be a human carcinogen. Damage to the liver and kidneys has been observed in rats chronically exposed to DX in drinking water. EPA has determined that lifetime exposure to DX at a concentration greater than 0.35 ppb in drinking water is associated with an excess cancer risk of greater than 1x10-6.
Dichloroethylene (1,1-DCE) is a volatile organic chemical used as a cleaning agent in chemical
manufacturing. It is sometimes found in groundwater as the result of decomposition of trichloroethane (TCA).
1,1-Dichloroethylene exhibits toxic effects to humans similar to TCE through inhalation and ingestion
exposures. This compound has anesthetic properties, and exposures to high concentrations may cause
nausea and vomiting (US EPA, 1985a). The CAG has classified 1,1-DCE as a possible human
carcinogen (Group C) for both inhalation and ingestion exposure routes (US EPA, 1989). The MCL is
7 parts per billion.
Tetrachloroethene (PCE) is similar to 1,1-DCE and may produce liver injury. PCE has been classified by the CAG as a possible human carcinogen (Group B2) via ingestion (US EPA, 1989).
Chloroform is a colorless, volatile liquid used as a solvent, and in the manufacturing of fluorocarbon refrigerants and plastics. Chloroform may have more serious effects on the liver than TCE and PCE (Doull et al., 1980). Chloroform has been classified by the EPA Carcinogen Assessment Group (CAG) as a probable human carcinogen (Group B2) via ingestion (US EPA, 1989). The MCL is 100 parts per billion.
Chromium occurs naturally with deposits of other metal ores. Chromium is used in alloys and electroplating. Various chromium compounds have widely varying human health effects. Chromium compounds in the trivalent (+3) state are of a low order of toxicity. In the hexavalent (+6) state, chromium compounds are irritants and corrosive and can enter the body by ingestion, inhalation, and through the skin (Sittig, 1981). Hexavalent chromium may cause liver and kidney damage, internal bleeding, and respiratory disorders (US EPA, 1985b). Hexavalent chromium has been designated by the CAG as a human carcinogen (Group A) via inhalation (US EPA, 1989). The MCL is 100 parts per billion.
Who is Involved
This site is being addressed through actions by Federal, state and local agencies and the potentially responsible parties.
The following is a summary of Potentially Responsible Parties (PRPs) which EPA has identified at the TIAA. PRPs for the Airport Property and TARP (also known as Area A) include the City of Tucson, Raytheon (TARP only), the U.S. Air Force, McDonnel Douglas Corporation, Tucson Airport Authority, and General Dynamics Corporation. Burr-Brown has been identified as a PRP for the eastern-most part of Area B contamination. EPA named these PRPs due to their roles as owners or operators of facilities that disposed hazardous substances (such as TCE) to the environment. EPA has enforceable legal settlements (such as consent decrees) requiring the cleanup of each of those three project areas. Contamination from the former West Cap Property is being addressed by EPA as there are no viable PRPs at that facility.
The AFP44 and Air National Guard Base are site project areas that are federally owned facilities with AFP44 being operated by Raytheon Missile Systems. Under the Superfund law (CERCLA), the federal agencies in charge of these facilities, the U.S. Air Force and the National Guard Bureau respectively, are authorized to take the lead for the investigation and cleanup of their properties. EPA and the State of Arizona provide oversight of the federal agencies’ cleanup.
In March 1990, a Consent Decree was signed between the EPA and Burr-Brown Corporation requiring Burr-Brown to clean up the eastern-most part of "Area B". In June 1991, a Consent Decree was approved for the cleanup of the TARP plume by the PRPs. EPA and the National Guard Bureau signed a Federal Facilities Agreement (FFA) in 1993. In February 2000, a Consent Decree was signed between EPA and the PRPs for the cleanup of the Airport Property. EPA, ADEQ, and the Air Force signed a FFA in November 2011 for Plant 44.
Investigation and Cleanup Activities
This site is being addressed in two stages: immediate actions, known as removal actions, and long-term remedial actions focusing on cleanup of groundwater and soils.
Immediate Actions: In 1981, the City of Tucson began closing all municipal wells that exceeded the State health levels and notified private well users of potential risks. EPA’s work to monitor water quality in private wells is ongoing. In 1991, contaminated sludges from a concrete sump were removed from the airport. In 1997, PCB-contaminated soils were removed from a residential area near the airport.
1: Air Force Plant #44/Raytheon
Groundwater: The regional aquifer cleanup consisting of a 1,500 gallon per minute (gpm) pump and treat system started up in 1987. The original air stripper system has been replaced by a Advanced Oxidation Process (AOP) treatment system that addresses all contaminants of concern in the main contamination plume south of Los Reales Road. The AOP system utilizes less energy and provides for the treatment of 1,4-dioxane which was not identified as a contaminant of concern until the early 2000s.
Soils: Ongoing soil cleanup has achieved the removal of an estimated 100,000 tons of metal contaminated soils and sludges. It should be noted that 80,000 of the 100,000 tons originated from the removal of lined RCRA ponds. Metal soils cleanup was completed in 2001 and the soils vacuum extraction cleanup systems were shut down in the early 2000s. On-going soils remediation is focused on pilot testing for in-situ treatment of subsurface soils that may be a source of groundwater contamination and reviewing well construction of the older extraction wells to optimize the remediation efforts.
2: Tucson Airport Remediation Project (TARP), also known as Area A or Tucson Airport West
Groundwater: In 1988, EPA selected a remedy to treat the groundwater in Area A (the main groundwater contamination plume north of Los Reales Road) by pumping and air stripping the contaminated groundwater, followed by discharging the treated water to the municipal water distribution system. The air emissions from the treatment process are first filtered using granular activated carbon. The regional aquifer cleanup, consisting of a 4,000 to 6,000 gpm pump and treat system, started in 1994 and has removed over 3,200 lbs of VOCs to date. This groundwater treatment plant provides clean drinking water to about 50,000 people, approximately 9% of Tucson’s water users. The system is expected to remain in operation until at least the year 2025.
Soils: There is no soil contamination associated with this project area.
3: Texas Instruments (Formerly Burr-Brown Corporation)
Groundwater: The remedy for TIAA Area B which includes Texas Instruments, Arizona Air National Guard, and West-Cap was changed from pump and treat to In-Situ Chemical Oxidation (ISCO) in a Amendment to the Record of Decision that was issued in April 2012. Based on the various pilot tests performed in TIAA Area, it was determined that an ISCO remedy will be a more efficient and cost effective method to restore groundwater. Texas Instruments will be performing an additional minor pilot test with ISCO that will be incorporated into the Remedial Design scheduled for 2015.
4: Arizona Air National Guard
Groundwater: The remedy for TIAA Area B which includes Arizona Air National Guard, Texas Instruments, and West-Cap was changed from pump and treat to In-Situ Chemical Oxidation (ISCO) in April 2012. The previous 150 gpm pump and treat system which started operations in 1997 was shut down in May 2012. The Arizona Air National Guard is currently performing a rebound test on the groundwater extraction system. The Arizona Air National Guard is expected to submit the Remedial Design to EPA and the State in 2014.
Soils: A SVE soil cleanup began in April 1997 and has removed sixty-four (64) lbs of VOCs to date. The SVE cleanup at this project area was completed in 1998.
5: Airport Property
Groundwater: In 2000, the PRPs began working on the design of a air stripping groundwater treatment system with vapor phased granular activated carbon to clean up a highly contaminated shallow groundwater zone. Due to the existence of pure liquid TCE in the shallow groundwater zone, in a low permeable clay unit underneath the “Three Hangars Area”, EPA has determined that a two-acre region of groundwater cannot be restored to drinking water quality. EPA has required the hydraulic containment of contamination in this two-acre zone in perpetuity. As with all other portions of the aquifer at the TIAA site, the remaining portions of this groundwater unit is set for full restoration to drinking water quality. Construction of this Three Hangars treatment plant was completed in October 2007.
Soils: In 1991 and 1995, the PRPs conducted removals of VOC and polychlorinated biphenyl [PCB] contaminated sludges from this property. In 1997, a PCB soil cleanup removed 10,000 tons of contaminated soil mostly from a nearby residential area. Construction of soil vapor extraction systems to clean up the remaining soils began in 2007. As of November 2012, the field work associated with the PCB Remedy has been completed and currently working on finalization of the reports.
Landfill Remedy: EPA approved the Remedial Action Completion Report in September 2013 for the Landfill Remedy and the remedy is considered complete.
6: Former West-Cap of Arizona property and West Plume B
Groundwater:The remedy for TIAA Area B which includes West-Cap, Arizona Air National Guard, and Texas Instruments was changed from pump and treat to In-Situ Chemical Oxidation (ISCO) in April 2012 The contract for the Remedial Design for West-Cap was finalized in October 2012. The 2012 ROD Amendment for TIAA Area B also selected MNA as the remedy for West Plume B.
7. 1,4-DX at TARP
Groundwater: Work is underway to complete a focused remedial investigation for 1,4-dioxane in groundwater at TARP. Initial field work began in February 2010 and the Focused RI Report will include discussions on the nature and extent of contamination and a baseline risk assessment related to 1,4-dioxane.
In 1992, leaders from the activist group, Southwest Network of Economic and Environmental Justice (SWNEEJ), met with EPA Region 9 management to discuss ways EPA could better address the needs of minority or low-income communities living near Superfund sites. As a result of these discussions, and the issuance of Federal Executive Order on Environmental Justice, EPA Region 9 implemented several new community-oriented actions at its Superfund sites. For example, at the Tucson Airport Superfund site, in addition to its work to oversee and implement cleanup at the site, EPA, with the help of other government agencies, proposed and carried out more than fifteen projects to address the special needs and concerns of Tucson's Southside community. These projects included the formation of a Unified Community Advisory Board (UCAB), a $30,000 Environmental Justice Grant to the El Pueblo Clinic, a TCE Superfund Information Library and the sponsorship of two middle school teachers from Southside's Sunnyside School District to attend EPA's environmental education teachers workshop in Baltimore.
Cleanup Results to Date
Contaminated drinking water supplies have been removed from service, and actions have been taken to control further contamination at the site. Significant progress has been made in identifying and cleaning up soil and groundwater contamination. A total of more than 40 billion gallons of groundwater has been treated and more than 130,000 pounds of VOCs removed from soils and groundwater throughout the site. Groundwater cleanup actions continue in all areas with additional cleanup systems scheduled for the future. In addition, 100,000 tons of metals, 10,000 tons of PCB-contaminated soils and 2,000 tons of PCB/VOC contaminated sludges have been removed. In 1994, EPA and Pima County officials completed a study that concluded that no known private well users on the south side of Tucson are currently drinking contaminated groundwater. The general public is not being exposed to the Superfund site contaminants.
Potentially Responsible Parties
Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.
Mr. George Warner
Title: Project Manager, United States Air Force
1801 Tenth St, Building 8, Site 2
Wright-Patterson AFB, Ohio 45433-7626
Phone: (937) 255-3241
Mr. Fred E. Brinker
Tilte: Project Manager, Airport Property
Address: Tucson Airport Authority
7005 South Plummer Ave
Tucson, Arizona 85706
Phone: (520) 573-4873
Mr. Jeff Biggs
Title: Project Manager, Tucson Water
Address: TARP Water Operations Superintendent
4401 South Tucson Estates Pkwy
Post Office Box 27210
Tucson, Arizona 85726-7210
Phone: (520) 349-2441
Mr. Gregory Wills
Title: Project Manager, Arizona Air National Guard
Address: Environmental Division (CEV)
3500 Fetchet Ave
Andrews Air Force Base, Maryland 20762
Mr. Joe Bauer
Title: Project Manager, Texas Instruments
Texas Instruments Incorporated
13588 North Central Expressway, Mail Stop 3734
Dallas, Texas 75243
Documents and Reports
Public Meetings: - Unified Community Advisory Board (UCAB)- UCAB is a forum where stakeholders work together to resolve issues and participate in the cleanup process at the Tucson International Airport Area Superfund Site. Meetings for the UCAB are held quarterly on the third Wednesday in January, April, July, and October in the Activity Center at the El Pueblo Neighborhood Center on 101 W. Irvington Road in Tucson. (Please contact either of the current Co-chairs: Yolanda Herrera (520) 991-3307, or Mary Aycock (415) 972-3289 for more information.)
- The Unified Community Advisory Board (UCAB) is seeking new board members! Please join us at our next meeting.
- If you or a local group would like to get more involved and/or would like to have EPA attend a meeting, give a presentation, answer questions, etc., please contact the Community Involvement Coordinator, Sarah Cafasso, at (415) 972-3076.
Public Information Repositories
The public information repositories for the site are at the following locations:
Tucson Public Library
El Pueblo Neighborhood Center
101 W. Irvington Road
Tucson, AZ 85714
EPA Site Manager
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
400 W. Congress, Suite 433
Tucson, AZ 85701
After Hours (Emergency Response)